Balloon structure and balloon catheter

ABSTRACT

An inflatable balloon structure ( 10 ) for catheters, such as a catheter for angioplasty or for depositing an endolumenal prosthesis or stent in a duct, for example, a vascular duct, the balloon structure being of predominant longitudinal extent with a proximal end and a distal end, and being suitable for performing an expansion in an object to be dilated, the balloon comprising a wall which has, transverse the longitudinal extent, at any point, an annular cross-section delimited externally by an outer surface which, at least in an intermediate portion thereof, is suitable for coming into contact with the object to be dilated, and internally by an inner surface which delimits an inflation chamber, in which at least one wall cavity ( 19 ) is provided in the wall and is formed within the annular cross-section which delimits the inflation chamber so as to be disposed between the outer surface and the inner surface, the cavity extending without interruptions and/or openings, longitudinally relative to the balloon structure, between the proximal end and the distal end.

The subject of the present invention is a balloon structure and acatheter comprising the balloon structure.

The present invention relates in particular to an inflatable balloonstructure for catheters such as, for example, a catheter for angioplastyor for depositing an endolumenal prosthesis or stent in a duct, forexample, a vascular duct.

One of the main requirements in the field is to provide balloonstructures which, when inserted in a catheter, allow paths to befollowed by the catheter-even if the paths are tortuous as those ofblood vessels, in particular but not exclusively coronary vessels, maybe.

A further requirement of these structures is for the catheter providedwith the structure to be capable of being oriented correctly, even whenthere are branches in the vascular duct, in particular but notexclusively enabling the catheter to perform even quite abrupt changesin direction.

Some solutions proposed for satisfying these requirements are known butthey are not completely satisfactory.

For example, catheters with balloon structures which at least partiallysatisfy these requirements are known from U.S. Pat. No. 5,061,273(YOCK), U.S. Pat. No. 4,762,129 (BONZEL), U.S. Pat. No. 4,545,390(LEARY), U.S. Pat. No. 4,299,226 (BANKA), U.S. Pat. No. 4,195,637(GRUNTZIG), U.S. Pat. No. 4,877,031 (CONWAY), U.S. Pat. No. 4,921,483(WIJAY), U.S. Pat. No. 4,944,745 (SOGARD), U.S. Pat. No. 4,964,853(SUGIYAMA), U.S. Pat. No. 5,032,113 (BURNS), U.S. Pat. No. 5,090,958(SAHOTA), U.S. Pat. No. 5,330,499 (KANESAKA), U.S. Pat. No. 6,530,938(LEE), U.S. Pat. No. 6,491,619 (TRAUTHEN), U.S. Pat. No. 5,895,405(INDERBITZEN), U.S. Pat. No. 6,027,475 (SIRHAN), U.S. Pat. No. 5,980,486(ENGER), U.S. Pat. No. 5,743,875 (SIRHAN),. U.S. Pat. No. 5,496,346(HORZEWSKI), U.S. Pat. No. 5,472,425 (TEIRSTEIN).

A further important requirement in the field is to provide a balloonstructure which permits the production of catheters with largeballoon-inflation cavities or, in other words, with inflation chambersthat are free of large obstructions and which permit rapid inflationand, above all, rapid deflation of the balloon so as to re-establishfree circulation quickly when the catheter is used to dilate the wallsof a blood vessel or to deposit an endolumenal prosthesis therein.

Some solutions proposed for satisfying these requirements, whichconflict with the former above-mentioned requirements, are known but arenot entirely satisfactory.

For example, catheters with balloon structures which at least partiallysatisfy these requirements are known from U.S. Pat. No. 4,983,167(SAHOTA), U.S. Pat. No. 5,315,747 (SOLAR), U.S. Pat. No. 6,394,995(SOLAR), U.S. Pat. No. 6,007,517 (AMDERSON), U.S. Pat. No. 5,413,557(SOLAR), U.S. Pat. No. 5,383,853 (JUNG), U.S. Pat. No. 5,690,642(OSBORNE), U.S. Pat. No. 5,921,958 (RESSEMANN), U.S. Pat. No. 5,458,639(TSUKASHIMA), U.S. Pat. No. 5,980,484 (RESSEMANN), U.S. Pat. No.5,575,771 (WALINSKY), U.S. Pat. No. 5,549,557 (STEINKE), U.S. Pat. No.5,549,556 (NDONDO-LAY), U.S. Pat. No. 5,569,199 (SOLAR), U.S. Pat. No.5,520,647 (SOLAR), U.S. Pat. No. 5,882,336 (JANACEK).

However, none of the solutions cited above succeeds in satisfying all ofthe requirements simultaneously.

The object of the present invention is to devise and make available aballoon structure and a balloon catheter which satisfy theabove-mentioned requirements.

This object is achieved by means of a balloon structure formed inaccordance with claim 1.

This object is also achieved by a balloon catheter according to claim34.

Further embodiments of the balloon structure and of the catheteraccording to the invention are described in the dependent claims.

Further characteristics and the advantages of the balloon structure andof the catheter according to the invention will become clear from thefollowing description of preferred embodiments which are given by way ofnon-limiting example with reference to the appended drawings, in which:

FIG. 1 is a section through an embodiment of a balloon structure,

FIG. 2 is a section transverse the axis of the balloon structure of FIG.1, taken on the line II-II,

FIG. 3 is a section through a second embodiment of the balloonstructure,

FIG. 4 is a section transverse the axis of the balloon structure of FIG.3, taken on the line IV-IV,

FIG. 5 is a transverse section through an extruded duct suitable for theproduction of a balloon structure, shown prior to its deformation,

FIGS. 6, 7 and 8 show three transverse sections through ducts coextrudedin several materials, shown after their deformation to form balloonstructures,

FIG. 9 is a perspective view of a step in the production of a balloonstructure,

FIG. 10 is an enlarged detail of the distal portion of the balloonstructure of FIG. 9, in which the inflation cavities and a guide-wirewall cavity are shown,

FIG. 11 is a perspective view of a detail of the proximal portion of theballoon structure during a second step of the production of the balloonstructure,

FIG. 12 is a perspective view of a third step in the production of theballoon structure,

FIG. 13 shows, in longitudinal section, a first step in the productionof a catheter comprising a balloon structure,

FIG. 14 shows a further step in the production of a shaft of thecatheter comprising the balloon structure,

FIG. 15 is a side view of a catheter comprising a balloon structure,

FIG. 16 is a longitudinal section through a detail of the distal portionof the catheter of FIG. 15,

FIG. 17 is a transverse section through the balloon structure of thecatheter of FIG. 16, taken on the line XVII-XVII,

FIG. 18 shows, in longitudinal section, a further detail of the distalportion of the catheter of FIG. 15,

FIG. 19 is a side view of a catheter comprising a further embodiment ofthe balloon structure,

FIG. 20 is a longitudinal section through a detail of the distal portionof the catheter of FIG. 19,

FIG. 21 is a transverse section through the balloon structure of thecatheter of FIG. 20, taken on the line XXI-XXI,

FIG. 22 is a side view of a catheter comprising yet another embodimentof the balloon structure,

FIG. 23 shows, in section, a detail of the shaft of the catheter of FIG.22, indicated by the arrow XXIII,

FIG. 24 is a section through a proximal connector of the catheter ofFIG. 22, indicated by the arrow XXIV,

FIG. 25 is a longitudinal section through a detail of the distal portionof the catheter of FIG. 22,

FIG. 26 shows, in longitudinal section, the tip of the catheter of FIG.25, indicated by the arrow XXVI in that drawing,

FIG. 27 is a transverse section through the balloon structure of thecatheter of FIG. 25, taken on the line XXVII-XXVII,

FIG. 28 is a transverse section through the balloon structure of thecatheter of FIG. 25, taken on the line XXVIII-XXVIII,

FIG. 29 is a longitudinal section through a tip for a balloon structure,

FIG. 30 shows a first step in the production of a tip for a balloonstructure,

FIG. 31 shows a second step in the production of a tip for a balloonstructure,

FIG. 32 shows a first step in the mounting of a balloon-structure tip ona distal portion of a balloon structure,

FIG. 33 shows a second step in the mounting of a balloon-structure tipon a distal portion of a balloon structure,

FIG. 34 shows a third step in the mounting of a balloon-structure tip ona distal portion of a balloon structure.

With reference to the above-mentioned drawings, a balloon structure isgenerally indicated 10.

The balloon structure is used in particular, but in non-limiting manner,as a part included in a catheter, for example, but in non-limitingmanner, a catheter for angioplasty or a catheter for depositing anendolumenal prosthesis or stent in a duct, for example, a vascular duct,for example, a coronary or peripheral duct.

The term “balloon structure” is intended to define herein a structurewhich comprises an inflatable or expandable balloon which can changefrom a contracted condition, when it is deflated, to an expandedcondition when it is inflated with a fluid. During its expansion, theballoon dilates, for example, the walls of a duct or, purely by way ofindication, displaces or shifts the plaque of a stenosis which ispartially or completely obstructing a lumen of a vessel, obstructing thefree flow of blood. The balloon structure can, for example, also be usedto expand endolumenal prostheses or stents so as to bring the stentsfrom a condition in which they are contracted onto or clinging to thecontracted balloon to an expanded condition for supporting the walls ofa portion of a vessel, for example, a blood vessel and for keeping thewalls stretched.

In a general embodiment, the balloon structure 10 is of predominantlylongitudinal extent, for example, it is a structure which extends abouta longitudinal axis a-a. The structure has a proximal end 11, a distalend 12, and an intermediate portion 13 of predefined longitudinal extentL, suitable for performing an expansion in an object to be dilated, forexample, the walls of a duct or an endolumenal prosthesis whichinitially clings to the intermediate portion in a contracted condition(FIG. 1).

The balloon structure 10 comprises a wall 14 which has, at any point, anannular cross-section 15 (FIG. 2) transverse the longitudinal axis a-a.The annular cross-section 15 is delimited externally by an outer surface16 which, at least in the intermediate portion 13, is suitable forcoming into contact with the object to be dilated. The section 15 isdelimited internally by an inner surface 17 which delimits an inflationchamber 18.

At least one wall lumen or cavity 19 is advantageously provided in thewall 14. This wall cavity is formed within the annular cross-section 15which delimits the inflation chamber 18 so as to be disposed between theouter surface 16 and the inner surface 17.

The wall cavity extends longitudinally relative to the balloon structure10, without interruption, between the proximal end 11 and the distal end12 so that, when the balloon structure is inflated or expanded, theouter surface 16 of the intermediate portion 13 has uniform curvaturearound the entire annular extent of the cross-section 15 in a sectiontransverse the longitudinal extent of the balloon structure 10 (FIGS. 1and 2).

The expression “extends without interruption” is intended mainly but notexclusively to mean without diverting partitions and/or openings, forexample, lateral apertures facing from the wall cavity 19 towards theinflation chamber 18 or lateral apertures which open in the outersurface 16 of the active portion L of the balloon structure 10, forexample, the intermediate portion 13. As can be seen, for example, fromFIGS. 1 and 2, by virtue of the wall cavity disposed in the wall of theballoon structure, the inflation chamber 18 is free of any impediment toa free flow of fluid into and out of the chamber. Moreover, the balloonstructure 10 does not have on the outer surface 16 any obstacles to itsfree rotation, for example, to the rotation or twisting of a cathetercomprising the balloon structure about itself in a narrow vessel.

According to a first embodiment, when the balloon structure is inflatedor expanded, the outer surface 16 of the intermediate portion 13 is freeof protuberances or recesses such as, for example, protuberances createdby a duct associated with the. annular section externally to form anoverall “8”-shaped cross-section. Instead, when the inflation chamber 18is expanded, the balloon structure 10 advantageously has the outersurface 16 which has an annular cross-section transverse thelongitudinal extent of the annular balloon structure, therefore saidouter surface is suitable for applying an uniform pressure all around.The outer surface 16 according to the present invention is also free ofrecesses such as a pocket or channel formed, for example, by a fold inthe balloon wall. Such protuberances or recesses would create obstaclesto the free twisting of a catheter comprising the balloon structure.Instead, by virtue of an outer surface which is free of protuberances orrecesses, when the balloon structure is in an expanded condition, itsangular position can be modified freely relative to its longitudinalaxis a-a when it is housed in a duct such as a blood vessel.

According to a further embodiment, the wall cavity 19 is within the wall14 which delimits the inflation chamber 19 for the whole of its extentthat affects the balloon structure (FIGS. 3 and 4).

When the balloon structure is inflated or expanded, the outer surface 16of the intermediate portion 13 is advantageously cylindrical.

Preferably, when the inflation chamber 18 is expanded, the balloonstructure 10 has an outer surface 16 of substantially circularcross-section transverse the longitudinal extent of the balloonstructure.

According to one embodiment, the balloon structure 10 comprises aproximal tubular portion 20 in the vicinity of the proximal end 11.

The balloon structure also comprises a proximal shank 21 which connectsthe proximal tubular portion 20 to the intermediate portion 13. Theproximal shank 21 advantageously has an internal taper angle “a” ofbetween 20 degrees. and 40 degrees. According to a further embodiment,the shank 21 has an internal taper angle of 30 degrees (FIG. 1).

According to one embodiment, the balloon structure 10 comprises a distalconnecting shank 22 between the intermediate portion 13 and a portion 23for connection to a distal catheter tip, as will be described in detailbelow. The distal shank 22 advantageously has an internal taper angle“b” of between 20 degrees and 40 degrees, preferably 30 degrees.

The wall cavity 19 is preferably separated from the inflation chamber 18by an internal portion 24 of the wall 14 (FIGS. 2 and 4). The cavity 19is separated from the outer surface 16 by an external portion 25 of thewall 14.

According to one embodiment, when the balloon structure is inflated orexpanded, the internal surface 17 of the intermediate portion 13 issmoothed, rounded, or free of sharp corners. When the balloon structureis inflated or expanded, the inner surface 17 of the intermediateportion 13 advantageously has an annular cross-section transverse thelongitudinal extent of the balloon structure.

According to one embodiment, the balloon structure 10 is produced froman extruded tube or duct, which is generally indicated 26 when it is notyet processed in order to become a balloon structure, and has at leasttwo cavities 18′ and 19, one of which, for example, the cavity 18′, issubsequently deformed to form the inflation chamber 18 of the balloonstructure 10 and is hereinafter also defined as the inflation cavity 18′(FIG. 5).

Prior to the deformation of a cavity 18′ thereof to form an inflationchamber 18, the extruded tube 26 advantageously has an at leastpartially flat partition 27 separating the at least two cavities. Afterthe deformation of a cavity 18′ to form an inflation chamber 18, theseparating partition 27 will advantageously constitute an internalportion 24 of the wall which separates the wall cavity 19 from theinflation chamber 18.

According to one embodiment, prior to the deformation of a cavity 18′ ofthe extruded tube 26 to form an inflation chamber 18, the extruded tube26 has a partition 27 for separating the at least two cavities 19 and18′; this partition has, in a cross-section transverse the extrudedtube, a minimum thickness t of between 55% and 100% of the minimumthickness T′ or T″ of the wall portion 14 or 25 which separates one ofthe cavities 18′ and 19 from the outer surface 16. Advantageously, priorto the deformation of a cavity 18′ of the extruded tube 26 to form aninflation chamber 18, the extruded tube 26 has a partition 27 forseparating the at least two cavities 18′ and 19; this partition has, incross-section transverse the extruded tube, a minimum thickness t ofbetween 60% and 70% of the minimum thickness T′ or T″ of the wallportion which separates one of the cavities 18′ and 19 from the outersurface 26 (FIG. 5).

According to one embodiment, a cavity 19 in the extruded tube 26 has apredefined width l19 and a predefined height h19. Advantageously, thecavity 19 has walls that are connected to one another and are preferablyformed, in cross-section, by arcs of predefined radius, that is, a firstarc, for example, the arc forming the inner wall of the external wallportion 25 of radius R191 concentric with the axis a-a of the tube 26,and then radii connecting the wall portion 25 to the partially flatpartition 27, for example, predefined radii R192 and R193. The secondcavity 18′ has a predefined width l18′ and height h18′ and delimitingwalls which are formed in cross-section, by arcs of predefined radius,that is, a first arc of radius R18′1, concentric with the axis a-a ofthe extruded tube 26, and successive arcs with predefined radii R18′2and R18′3, connected to the first arc and also connected to thepartition 27 (FIG. 5).

According to one embodiment, the balloon structure 10 is produced by theexpansion of an inflation cavity 18′ of a tube with at least twocavities 18′ and 19, the tube 26 being produced by coextrusion of atleast two materials; a first of these materials 28, when expanded, formsthe wall 14 or wall portion 24 which delimits the inflation chamber 18or separates the chamber 18 from the wall cavity 19. Advantageously, thematerial which delimits the inflation cavity 18′ prior to itsdeformation and the inflation chamber after its deformation is asemi-compliant or partially yielding material which is resistant to themaximum pressure predefined for the inflation of the balloon structure,such as, for example, nylon or a material with similar performance. Withfurther advantage, a second 29 of these materials forms at least a partof the wall portion 24, 25 which delimits the wall cavity 19. Forexample, the second material 29 forms the wall portion 25 whichseparates the wall cavity 19 from the outer surface 16. According to oneembodiment, the second material 29 has a greater flexibility than thefirst material 28 (FIGS. 6 and 7).

According to a further embodiment, the balloon structure 10 is producedby the expansion of an inflation cavity 18′ of a tube 26 with at leasttwo cavities 18′ and 19, the tube 26 being produced by coextrusion ofthree materials 28, 29 and 30. Advantageously, the wall cavity 19 islined or delimited by a layer of material 30 with a coefficient offriction such as to facilitate the sliding of a guide wire housed in thewall cavity 19 (FIGS. 7 and 8).

According to one embodiment, when the balloon structure is inflated orexpanded, the wall cavity 19 is separated from the inflation chamber 18by a wall portion 24 which has, in cross-section transverse thelongitudinal extent a-a of the balloon structure, a thickness t″ ofbetween 55% and 100% of the thickness T′″ of a wall portion 25 whichseparates the wall cavity 19 from the outer surface 16. Preferably, whenthe balloon structure 10 is inflated or expanded, the wall cavity 19 isseparated from the inflation chamber by a wall portion 24 which has, incross-section transverse the longitudinal extent a-a of the balloonstructure 10, a thickness t″ of between 60% and 70% of the thickness T′″of a wall portion 25 which separates the wall cavity 19 from the outersurface 16. Advantageously the internal wall portion 24 and the externalwall portion 25 are of equal minimum thickness (FIG. 6).

According to one embodiment, the inflation chamber 18 is closed in aleaktight manner onto an apex tip 31, leaving only apex access openings32, 33 to one or more guide-wire cavities 19 and 34 (FIGS. 16 and 20).

According to one embodiment, an inflatable balloon structure forcatheters comprises a wall which has, transverse a longitudinal extentthereof, at any point, an annular cross-section delimited externally byan outer surface which, at least in an intermediate portion, is suitablefor coming into contact with the object to be expanded, and internallyby an inner surface which delimits an inflation chamber. At least onewall cavity is provided in this wall and is formed within the annularcross-section which delimits the inflation chamber so as to be disposedbetween the outer surface and the inner surface, the cavity extendingwithout interruptions and/or openings, longitudinally relative to theballoon structure, between the proximal end and the distal end.

A method for the production of the balloon structure 10 is described byway of example below.

First of all, a tubular duct 26 of predominant longitudinal extent a-ais provided, the tubular duct 26 having at least two cavities 18′ and 19which extend along its entire longitudinal extent and are kept separatedfrom one another, for example, by a partition 27 which is preferablyintegral with the structure of the tubular duct. The at least twocavities 18′ and 19 extend from proximal openings to distal openingsprovided at the proximal end 11 and at the distal end 12 of the duct,respectively.

At least a portion of the duct is then inserted in a die provided with acavity that is widened to form the desired shape of the expanded balloonand at least one of the distal or proximal openings of the duct isclosed. In particular, one of the openings of a cavity 18′ which isintended to form the inflation chamber 18 of the balloon structure isclosed in a leaktight manner. Alternatively, the cavity or both cavitiesmay be closed in a leaktight manner by obstructing or choking a portionof the duct which is disposed outside the die.

The portion of duct that is disposed in the die is then heated to atemperature which permits permanent deformation of the material or ofone of the materials of which the tubular duct is made. For example, ifthe duct is made of polyamide and/or nylon and/or Pebax™ and/orhigh-density polyethylene, with characteristics of a low coefficient offriction, or similar or equivalent materials, used alone or incombination by producing the duct by coextrusion, the die may be heatedto a temperature T of between 80° centigrade and 120° centigrade,preferably 100° centigrade.

At this point, fluid can be admitted under pressure to one of the twocavities, that is, the cavity 18′ which will form the inflation chamber18, so as to deform the wall 14 of the duct which delimits this cavity,causing it to fit against the walls of the widened cavity delimited bythe die, meanwhile, for example, the duct is stretched. If fluid underpressure is admitted solely to the cavity 18′ which will form theinflation chamber, the second cavity 19 remains incorporated in the wallthus deformed which delimits the inflation chamber 18. In particular,if, for example, the die is shaped so as to delimit a cylindrical cavityin order to produce a balloon with a cylindrical outer surface, thecavity to which the pressure is admitted deforms in a manner such thatthe wall 14 which delimits its inflation chamber will have a cylindricalouter surface 16 and the second cavity or wall cavity 19 will deform,remaining incorporated within the wall.

According to one embodiment, to prevent the second cavity 19 from beingclosed because of the deformation of the first cavity 18′ to form aninflation chamber 18, before fluid is admitted to one of the cavities18′ under pressure, a stylet 39 is inserted in the other cavity. Thisprevents the deformation of the heated wall from blocking this othercavity 19.

According to a further embodiment, the stylet is covered with non-stickmaterial such as Teflon™ which enables the stylet to be removed from thecavity or wall cavity 19 after the deformation of the inflation chamber18 at high temperature, without the wall portion 24 which delimits thewall cavity 19 being welded to the stylet or to other wall portions 25,blocking the cavity or preventing removal of the stylet.

As a result of the deformation of the duct with two cavities in the die,a balloon structure 10, for example, as described above, is obtained.

Further variants may also be provided. For example, it is possible touse, initially, a duct with three or more cavities in which only one ofthese cavities is deformed at high temperature to form the inflationchamber as described above, so as to leave the other two or morecavities incorporated in the wall of the balloon, for example, inpredetermined positions. With reference to a cross-section transversethe longitudinal extent of the duct or of the balloon structure thusobtained, the cavities incorporated in the wall of the balloon may bespaced apart angularly by 180 degrees, that is on opposite sides of thecross-section with respect to the inflation chamber, or may be spacedapart by angles of 120 degrees, or even 90 degrees.

The description relating to a possible embodiment of a catheter is givenbelow. First of all, the balloon structure 10, produced as describedabove, is cut with a tool 35 in a proximal region 11 relative to theballoon so as to leave, for example, from the balloon towards theproximal end, a tubular portion 20 which has a length lt which variesfrom 1 mm to 150 mm. Preferably, the balloon structure 10 is cutproximally at about 1.5 mm-2.5 mm from the balloon or from the proximaltransition region or shank 21, which transition region is providedbetween the intermediate portion 13 of maximum extent of the balloon anda proximal tubular portion 20. In other words, the proximal tubularportion 20 is cut so that it is about 1.5 mm-2.5 mm long. This isperformed, for example, so as to modify the characteristics of thecatheter 36 which are to be obtained immediately in front of orproximally relative to the balloon. It is in fact preferable, forexample, to have different characteristics for the portion of thecatheter in which the balloon is provided, in comparison with theportion of the catheter in which the shaft 37 or the thrust body isprovided. The tip 31 and the balloon structure 10 of the catheter arepreferably made of softer and more flexible material than the shaft 37which has to exert the necessary thrust on the balloon structure 10 forit to be inserted in the desired duct (FIGS. 9 and 10).

With reference to the die for producing the balloon structure, this canbe shaped in a manner such as to delimit a cavity for producing acylindrical or oval balloon with two connecting portions or sections orconnecting shanks 21 and 22 between the intermediate portion or section13, which is, for example, cylindrical, and the proximal and distaltubular portions or sections 20 and 23. These shanks 21 an 22 arepreferably frustoconical. The shanks have, for example, a taper variablefrom 20 degrees to 40 degrees and are preferably identical for theproximal shank and for the distal shank.

According to one embodiment, a proximal aperture 38 or lateral proximalaperture of the wall cavity 19 is produced a predetermined distance fromthe balloon or, for example, from the proximal shank 21, in thedirection away from the balloon. For example, the lateral proximalaperture 38 may be produced by removing a section of the wall portion 25which separates the wall cavity 19 from the outer surface 16. Forexample, this operation is performed with the insertion of a stylet 39which protects the wall portion 24 that separates the wall cavity 19from the inflation chamber 18′.

A proximal tube is then connected or joined to the balloon structure 10,forming the shaft 37 of the catheter 36. First of all, a not adhesive,such as PTFE, coated stylet or a Teflon™-coated stylet is fitted in theinflation cavity 18′ which, as described above, is formed by the portionof the cavity which is in the proximal tubular portion 20 and which hasnot been transformed into the inflation chamber 18, and a tube or distalsection of the shaft 40, for example, a single-cavity duct or a ductwith solely an inflation chamber 18′, is fitted thereon (FIGS. 12 and13).

The distal section of the shaft 40 will preferably be inserted in theproximal tubular portion 20 for a distance which ensures leaktightnessand sufficient structural strength and which at the same time does notstiffen the shaft 37 locally, for example, the distal section of theshaft 40 is inserted for a distance of 2 times the thickness of thetubular portion to be welded, such as 1 mm-3 mm, preferably a distanceof 1.5 mm-2.5 mm. When the overlap has been formed, it is welded,forming a joint, for example, by means of a jet of hot air at between180° centigrade and 220° centigrade, in any case at a temperaturegreater than the melting temperature of the used materials, the balloonstructure being protected, for example, by a screen. The region to bewelded is covered with a film or a tubular piece of a thermo-retractilematerial which deforms the joint region during the heating of theregion, and permits a gradual transfer of heat and which can be removedafter the welding, for example, polyefin. To ensure that the inflationcavity 18′ is not blocked during the welding, a Teflon-coated stylet 39is kept therein.

In order to vary the stiffness and the thrust capacity of the shaft 37of the catheter 36 along its longitudinal extent, an intermediate shaftsection 41, for example stiffer than the distal section 40, may be fixedor joined proximally to this first, distal shaft section. In this case,the inflation cavity 18′ which is also present in the intermediate shaftsection 41 is again protected by the insertion of a Teflon-coated stylet39. The welding is performed by the same procedures as described above.In this case, the shaft sections are again overlapped for a portion ofpredetermined extent s2 which ensures the necessary structural strengthand at the same time the desired flexibility. The joints between theballoon structure and the distal and intermediate shaft sections areillustrated schematically in FIGS. 12, 13 and 14, purely to show theircharacteristics. After welding, the regions affected, that is the jointregions, will nevertheless have external dimensions approximately equalto those of the larger-dimensioned duct, or even smaller.

An embodiment of an apex tip, for example, as shown in FIG. 29, to beconnected or joined to a distal end of a balloon structure, as describedabove to form an apex aperture for the wall cavity and a leaktightclosure of the inflation chamber, is described below.

First of all, an apex tube 50 is provided, the tube 50 having a proximalend 51 and a distal end 52 in which an apex opening 32 is provided (FIG.30).

Then a proximal portion of the apex tube 50 is widened, for example, bysquashing or flaring the tube on opposite sides, rendering the cavityoval locally.

A connecting tube 53 to be inserted in a wall cavity 19 of a balloonstructure 10 is then provided; the connecting tube 53 has a cavitysuitable for housing a guide-wire.

With the aid of a stylet 39, for example, a Teflon-coated stylet, thedistal portion of the connecting tube 53 is fitted in the widenedportion of the apex tube 50 so as to form a continuous cavity between aproximal opening 54 of the connecting tube 53 and the apex opening 32 ofthe apex tube 50.

According to one particular embodiment, an anchoring tube 55 is providedfor insertion with a distal portion thereof in the widened apex tube 50so as to be disposed at least partially beside the connecting tube 53.The anchoring tube 55 is suitable for anchoring a thrust wire 44 and issuitable for the leaktight closure of the distal opening of theinflation chamber 18 of a balloon structure 10 (for example, as shown inFIG. 18). The welding between the apex tube 50, the connecting tube 53,and the anchoring tube 55 is then performed in a manner similar to thatdescribed above, taking particular care not to close the cavity 19 byinserting a Teflon-coated stylet 39 (FIG. 31) beforehand. Whilstperforming the joining, it is necessary to take care that the connectingtube projects from the apex tube by a predetermined distance lpa which,for example, is variable between 1.5 mm and 2.5 mm, so as to allow theconnecting tube 53 to be inserted in the wall cavity 19 whilst avoidingexcessive stiffening of the distal portion of the balloon structure andat the same time ensuring the necessary structural strength.

The apex tip 31 is then ready to be connected to a balloon structure.The thrust wire 44 is inserted in the inflation cavity 18′ in theinflation chamber 18, and then in the inflation cavity 18′ of thecatheter shaft 37 until the anchoring tube 55 is inserted in a leaktightmanner in the distal opening of the inflation cavity 18′ (FIG. 32).During this operation, the connecting tube 53 is simultaneously insertedin the wall cavity 19 (FIG. 33). The apex tip 31 is then welded to theballoon structure by the method described above (FIG. 34), with suitablescreening of the balloon structure 10. Finally, the stylet is removedfrom the wall cavity 19.

According to a further embodiment, a second connecting tube is providedfor insertion with a distal portion thereof in the apex tube so as to bedisposed at least partially beside the first connecting tube. The secondconnecting tube is suitable for forming a second guide-wire cavity 34between a proximal opening of the second connecting tube and the apexopening 33 of the apex tube, and is suitable for the leaktight closureof a distal opening of an inflation chamber of a balloon structure. Thissecond connecting cavity 34 is suitable for connection to a guide-wireduct 45 which is provided inside the catheter (FIG. 20) in oneembodiment.

According to one embodiment, a catheter apex tip is thus produced. Thetip has a proximal end and an apex end and comprises a tubular apexportion disposed in the vicinity of the apex end, and a proximalconnecting tube disposed in the vicinity of the proximal end. Theproximal connecting tube is partially housed with a distal portionthereof inside a proximal portion of the apex tube. The connecting tubeis connected to the apex tube so as to form a cavity which extendswithout interruption from an opening disposed at the proximal end of theconnecting tube to an opening disposed at the apex end of the apex tube.The connecting tube is suitable for connection to a wall cavity suitablefor housing a guide wire, which cavity is provided within a wall thatdelimits a balloon inflation chamber. The apex tube is fitted proximallyand in a leaktight manner in a distal opening of a balloon structure forthe leaktight closure thereof.

According to a further embodiment, a catheter tip has a proximal end andan apex end and comprises a tubular apex portion disposed in thevicinity of the apex end, a proximal connecting tube disposed in thevicinity of the proximal end, and a tube for anchoring a thrust wire orrod, also disposed in the vicinity of the proximal end. The anchoringtube and the proximal connecting tube are arranged at least partiallyside by side and are housed with respective distal portions inside aproximal portion of the apex tube. The connecting tube is connected tothe apex tube so as to form a cavity which extends without interruptionfrom an opening disposed at the proximal end of the connecting tube toan opening disposed at the apex end of the apex tube. The connectingtube is suitable for connection to a wall cavity suitable for housing aguide wire, which cavity is provided within a wall that delimits aballoon inflation chamber. The anchoring tube is closed distally and ina leaktight manner and is suitable for connection to a distal opening ofa balloon structure for the leaktight closure thereof and for theanchorage of a distal end of a thrust wire. The anchoring tube, theconnecting tube, and the apex tube are advantageously welded to form asingle body (FIGS. 16, 18, 25, 26 and 29).

According to yet another embodiment, a catheter tip has a proximal endand an apex end and comprises a tubular apex portion disposed in thevicinity of the apex end, a first proximal connecting tube disposed inthe vicinity of the proximal end, and. a second connecting tube alsodisposed in the vicinity of the proximal end. The first connecting tubeand the second connecting tube are arranged at least partially side byside and are housed with respective distal portions inside a proximalportion of the apex tube. The first and second connecting tubes areconnected to the apex tube so as to form cavities which extend withoutinterruption from an opening disposed at the proximal ends of theconnecting tubes to at least one opening disposed at the apex end of theapex tube. The first connecting tube is suitable for connection to awall cavity suitable for housing a guide wire, which wall cavity isprovided within a wall that delimits a balloon inflation chamber. Thesecond connection tube is suitable for connection to a guide-wire ductwhich is suitable for housing a guide wire and is disposed inside theballoon structure. The first and second connecting tubes and the apextube are advantageously welded to form a single body (FIG. 20).

The connection of the balloon structure to the shaft and to the apex tipproduces a catheter as shown in FIGS. 15 to 28.

According to one embodiment, a catheter 36 comprises an apex tip 31which has a proximal end and an apex end and comprises a tubular apexportion 50 disposed in the vicinity of the apex end, and a proximalconnecting tube 53 disposed in the vicinity of the proximal end. Theproximal connecting tube 53 is partially housed with a distal portionthereof inside a proximal portion of the apex tube 50. The connectingtube is connected to the apex tube so as to form a cavity which extendswithout interruption from an opening disposed at the proximal end of theconnecting tube to an opening disposed at the apex end of the apex tube.The connecting tube is connected to a wall cavity 19 suitable forhousing a guide wire. The wall cavity is provided within a wall thatdelimits an inflation chamber 18 of a balloon structure 10.

According to another embodiment, a catheter comprises an apex tip 31which has a proximal end and an apex end and comprises a tubular apexportion 50 disposed in the vicinity of the apex end, a proximalconnecting tube 53 disposed in the vicinity of the proximal end, and atube 55 for anchoring a thrust wire 44 or rod, also disposed in thevicinity of the proximal end. The anchoring tube 55 and the proximalconnecting tube 53 are arranged at least partially side by side and arehoused with respective distal portions inside a proximal portion of theapex tube 50. The connecting tube 53 is connected to the apex tube 50 soas to form a cavity which extends without interruption from an openingdisposed at the proximal end of the connecting tube to an opening 32disposed at the apex end of the apex tube. The connecting tube isconnected to a wall cavity 19 suitable for housing a guide wire, and thewall cavity is provided within a wall that delimits an inflation chamber18 of a balloon structure 10. The anchoring tube 55 is connected to adistal opening of a balloon structure for the leaktight closure thereofand for the anchorage of a distal end of a thrust wire 44 providedinside the balloon structure 10. In the catheter, the anchoring tube,the connecting tube, and the apex tube are advantageously welded to forma single body (FIGS. 15, 16, 18 and 22, 25).

According to yet another embodiment, a catheter comprises an apex tip 31which has a proximal end and an apex end and comprises a tubular apexportion disposed in the vicinity of the apex end, a first proximalconnecting tube disposed in the vicinity of the proximal end, and asecond connecting tube also disposed in the vicinity of the proximalend. The first connecting tube and the second connecting tube arearranged at least partially side by side and are housed with respectivedistal portions inside a proximal portion of the apex tube. The firstand second connecting tubes are connected to the apex tube so as to formcavities which extend without interruption from respective openingsdisposed at the proximal ends of the connecting tubes to at least oneopening disposed at the apex end of the apex tube. The first connectingtube is connected to a wall cavity suitable for housing a guide wire,which wall cavity is provided within a wall that delimits a ballooninflation chamber. The second connecting tube is connected to aguide-wire duct 45 suitable for housing a guide wire, the guide-wire-duct being disposed inside the balloon structure. The first and secondconnecting tubes and the apex tube are advantageously welded to form asingle body (FIGS. 19, 20 and 21).

According to one embodiment, a catheter comprises a thrust wire 44disposed inside the catheter shaft 37 that is connected proximally tothe balloon (FIGS. 16, 18 and 25).

A catheter advantageously comprises a guide-wire duct 45 which isdisposed inside the catheter shaft 37 that is connected proximally tothe balloon (FIGS. 20 and 21).

According to one embodiment, in a catheter, the wall portion whichseparates the wall cavity from the outer surface has an opening whichforms a lateral aperture 47 to allow a guide wire to be inserted in thewall cavity 19 or to emerge therefrom (FIG. 25).

According to one embodiment, a catheter comprises a balloon structure 10connected proximally to a shaft 37 which comprises an inflation cavity18′ or 49 that is connected to the inflation chamber 18 in a leaktightmanner for the flow of a fluid from the shaft to the inflation chamberand vice versa (FIGS. 16, 20 and 25).

According to a further embodiment, a catheter comprises a balloonstructure 10 connected proximally to a shaft 37 comprising a guide-wirecavity 46 that is connected to the wall cavity 19 in a leaktight mannerfor the passage of a guide wire (FIGS. 16 and 20).

According to one embodiment, a catheter comprises a guide-wire cavity 46disposed in the wall of the shaft 37 and separated from the outersurface of the shaft by a wall portion.

According to yet another embodiment, a catheter comprises a shaft whichhas an opening in the wall portion which separates the guide-wire cavityfrom the outer surface, which opening is suitable for the passage of aguide wire.

Advantageously, a catheter comprises a balloon structure 10 connectedproximally to a shaft comprising a guide-wire cavity 46 connected to thewall cavity 19 in a leaktight manner for the passage of a guide wire,the guide-wire cavity being provided in a guide-wire duct 40 providedinside the shaft 37 (FIGS. 16 and 20). With further advantage, the ductis connected in a leaktight manner to a lateral aperture 47 provided inthe outer wall of the shaft to allow a guide wire to be inserted in orto emerge from the guide-wire cavity of the guide-wire duct.

Preferably, a catheter comprises a shaft 37 which has a plurality ofportions formed with a plurality of ducts of predetermined longitudinalextent LC1, LC2 and LC3, relative to the apex end of the catheter.Advantageously, the shaft has a plurality of portions 40, 41 and 42formed with ducts made of different materials and/or with differentthicknesses, or with the insertion of a stiffening inner tube.

According to one embodiment, a catheter comprises a shaft which has aninflation cavity 49 in flow communication with the inflation chamber 18of the balloon structure and a thrust wire 44 having a distal end and aproximal end. The thrust wire is advantageously inside the inflationcavity 49. The thrust wire preferably extends along the entire length ofthe shaft. According to one embodiment, the thrust wire 44 is anchoredby its distal end to the balloon structure. The thrust wire 44 isadvantageously anchored by its distal end to the tip 31 of the catheter(FIGS. 16 and 17).

According to one embodiment, a catheter comprises a thrust wire 44connected by its proximal end to an inner tube that is present in theshaft.

A description of a method for the use of the catheter according to thepresent invention is given below, purely by way of example.

First of all, at least one guide wire is inserted in a vessel which isto be operated on. A catheter, provided with the above-described balloonstructure, is then fitted on the guide wire by passing the wire throughan apex guide-wire aperture and then sliding it through a guide-wirewall cavity which, at least for its section corresponding to the extentof the balloon, is disposed in the balloon wall, and causing the wire toemerge from a proximal aperture, relative to the balloon. The catheteris then inserted in the vessel, travelling along the guide wire untilthe balloon is disposed in the operation zone.

Advantageously a further step is provided for advancing the catheter onthe guide wire by pushing it by means of a thrust wire provided in thecatheter body.

It can be appreciated from the foregoing that, by virtue of theprovision of a structure as described above, there are no obstructionsinside the inflation chamber, so that rapid inflation and deflation ofthe balloon are facilitated. Alternatively, for a given performance withregard to balloon inflation and deflation speed, it is possible toproduce catheters of very limited transverse dimensions which can reacheven very small vessels. This catheter has also been found to beunusually flexible and easy to guide even along tortuous paths.

If the presence of a thrust wire reaching as far as the tip of thecatheter is required, it is possible to have direct transmission of thecontrol imparted to the catheter from the proximal connecting element 43to the tip, achieving greater precision and speed of operation.

In contrast with known catheters, it is also possible to provide athrust wire and a guide-wire duct in the catheter shaft without reducingperformance in comparison with known solutions. In other words, theinflation cavity is not reduced excessively even if a thrust wire and aguide-wire duct are provided inside the catheter shaft, so that anexcessive reduction in balloon deflation time is in any case avoided.Moreover, the catheter is not too stiff.

The solution proposed herein is also substantially more compact or lessbulky than known solutions.

Further advantages of the solutions proposed are:

the balloon structure proposed is inserted with extreme flexibility eveninto tortuous branches,

in particular, the provision of an outer surface with uniform curvaturerenders the shape of the balloon structure particularly capable ofpenetrating small ducts and obstructions, facilitates a uniformdistribution of pressure on an object to be dilated, and alsofacilitates the orientation of the balloon structure angularly relativeto its longitudinal axis (rotation or twisting of the catheter),

the fact that the guide-wire cavity is provided in the wall of theballoon structure means that no obstructions are created inside theinflation chamber so that the admission of fluid in order to inflate orexpand the balloon, as well as the discharge of the fluid in order tocontract the balloon and to release the cavity of the vessel promptly,for example, to permit the flow of blood in a blood vessel, areparticularly quick at constant overall dimensions of the catheter,

with the solution proposed, it is possible to lead the thrust wire andthe guide-wire or guide-cable cavity to the catheter tip simultaneously,

with the solution proposed, it is possible to guide the guide-wire in aguide-cable cavity having an extension equal or lower than the balloonstructure extension, in order to reduce the friction force exerted bythe guide-wire on the guide-cable cavity,

according to some embodiments, it is possible to maintain or to increasethe capacity of the inflation cavity or, for a given inflation cavity,it is possible to reduce the transverse dimensions of the catheter,enabling thrust wires of smaller cross-section to be used for a givencatheter stiffness, improving the ease of handling of the catheter andits ability to pass through obstructions, as well as reducing frictionduring the advance of the catheter in the vessel.

Naturally, variants and/or additions may be provided for the embodimentsdescribed and illustrated above.

In order to satisfy contingent and specific requirements, a personskilled in the art will be able to apply to the above-describedpreferred embodiment of the balloon structure and catheter manymodifications, adaptations and replacements of elements with otherfunctionally equivalent elements without, however, departing from thescope of the appended claims.

1-71. (canceled)
 72. An inflatable balloon structure for catheters, suchas a catheter for angioplasty or for depositing an endolumenalprosthesis or stent in a duct, for example, a vascular duct, the balloonstructure being of predominant longitudinal extent with a proximal endand a distal end, and being suitable for performing an expansion in anobject to be dilated, the balloon structure comprising a wall which has,transverse the longitudinal extent, at any point, an annularcross-section delimited externally by an outer surface which, at leastin an intermediate portion thereof, is suitable for coming into contactwith the object to be dilated, and internally by an inner surface whichdelimits an inflation chamber, in which: at least one wall cavity isprovided in the wall and is formed within the annular cross-sectionwhich delimits the inflation chamber so as to be disposed between theouter surface and the inner surface the cavity extending, withoutinterruptions and/or openings, longitudinally relative to the balloonstructure between the proximal end and the distal end so that, when theballoon structure is inflated or expanded, the outer surface of theintermediate portion has, in cross-section transverse the longitudinalextent of the balloon structure, uniform curvature around the entireannular extent of the cross-section.
 73. A balloon structure accordingto claim 72 in which, when the balloon structure is inflated orexpanded, the outer surface of the intermediate portion is free ofprotuberances or recesses.
 74. A balloon structure according to claim 72in which the wall cavity is within the wall which delimits the inflationchamber for the whole of its extent which affects the balloon structure.75. A balloon structure according to claim 72 which, when the balloonstructure is inflated or expanded, the outer surface of the intermediateportion is cylindrical.
 76. A balloon structure according to claim 72 inwhich, when the inflation chamber is expanded, the balloon structure hasan annular cross-section of the outer surface, transverse thelongitudinal extent of the balloon structure.
 77. A balloon structureaccording to claim 72 in which, when the inflation chamber is expanded,the balloon structure has a substantially circular cross-section of theouter surface, transverse the longitudinal extent of the balloonstructure.
 78. A balloon structure according to claim 72 in which theballoon comprises a proximal tubular portion in the vicinity of theproximal end.
 79. A balloon structure according to claim 72 in which theballoon comprises a proximal shank connecting the proximal tubularportion and an intermediate portion.
 80. A balloon structure accordingto claim 79, in which the proximal shank has an internal taper angle ofbetween 20 degrees and 40 degrees, preferably of 30 degrees.
 81. Aballoon structure according to claim 72 in which the balloon comprises adistal connecting shank between the intermediate portion and a portionfor connection to a distal catheter tip.
 82. A balloon structureaccording to claim 81, in which the distal shank has an internal taperangle of between 20 degrees and 40 degrees, preferably of 30 degrees.83. A balloon structure according to claim 72, in which the wall cavityis separated from the inflation chamber by an internal portion of thewall.
 84. A balloon structure according to claim 72, in which the cavityis separated from the outer surface by an external portion of the wall.85. A balloon structure according to claim 72, in which, when theballoon structure is inflated or expanded, the inner surface of theintermediate portion is smoothed, rounded, or free of sharp corners. 86.A balloon structure according to claim 72, in which, when the balloonstructure is inflated or expanded, the inner surface of the intermediateportion has an annular cross-section, transverse the longitudinal extentof the balloon.
 87. A balloon structure according to claim 72, in whichthe structure is produced from an extruded tube having at least twocavities, one of which is deformed to form the inflation chamber of theballoon structure.
 88. A balloon structure according to claim 87, inwhich, prior to the deformation of a cavity of the extruded tube to forman inflation chamber, the extruded tube has an at least partially flatpartition separating the at least two cavities.
 89. A balloon structureaccording to claim 87, in which, prior to the deformation of a cavity ofthe extruded tube to form an inflation chamber, the extruded tube has apartition separating the at least two cavities, which partition has, incross-section transverse the extruded tube, a minimum thickness ofbetween 55% and 100% of the minimum thickness of the wall portion whichseparates one of the cavities from the outer surface.
 90. A balloonstructure according to claim 87, in which, prior to the deformation of acavity of the extruded tube to form an inflation chamber, the extrudedtube has a partition separating the at least two cavities whichpartition has, in cross-section transverse the extruded tube, a minimumthickness of between 60% and 70% of the minimum thickness of the wallportion which separates one of the cavities from the outer surface. 91.A balloon structure according to claim 72, in which the balloonstructure is produced by the expansion of an inflation cavity of a tubewith at least two cavities, the tube being produced by coextrusion of atleast two materials, a first of these materials forming the wall or wallportion which delimits the inflation cavity.
 92. A balloon structureaccording to claim 91, in which the material which delimits theinflation cavity is a material that is semi-compliant or partiallyyielding but resistant to the maximum balloon-inflation pressure.
 93. Aballoon structure according to claim 72, in which the balloon structureis produced by the expansion of an inflation cavity of a tube with atleast two cavities, the tube being produced by coextrusion of at leasttwo materials, a second of these materials forming at least a part ofthe wall portion which delimits a wall cavity.
 94. A balloon structureaccording to claim 93, in which the second material forms the wallportion which separates the wall cavity from the outer surface.
 95. Aballoon structure according to claim 93, in which the second materialhas a greater flexibility than the first material.
 96. A balloonstructure according to claim 72, in which the wall cavity is coated withor delimited by a layer of material with a coefficient of friction suchas to facilitate the sliding of a guide wire housed in the wall cavity.97. A balloon structure according to claim 72, in which the balloonstructure is produced by the expansion of an inflation cavity of a tubewith at least two cavities, the tube being produced by coextrusion ofthree materials.
 98. A balloon structure according to claim 72, inwhich, when the balloon structure is inflated or expanded, the wallcavity is separated from the inflation chamber by a wall portion whichhas, in cross-section transverse the longitudinal extent of the balloon,a thickness of between 55% and 100% of the thickness of a wall portionwhich separates the wall cavity from the outer surface.
 99. A balloonstructure according to claim 72, in which, when the balloon structure isinflated or expanded, the wall cavity is separated from the inflationchamber by a wall portion which has, in cross-section transverse thelongitudinal extent of the balloon, a thickness of between 60% and 70%of the thickness of a wall portion which separates the wall cavity fromthe outer surface.
 100. A balloon structure according to claim 72, inwhich the inflation chamber is closed in a leaktight manner onto an apextip, leaving solely openings for access to one or more guide-wirecavities.
 101. An inflatable balloon structure for catheters, such as acatheter for angioplasty or for depositing an endolumenal prosthesis orstent in a duct, for example, a vascular duct, the balloon structurebeing of predominant longitudinal extent with a proximal end and adistal end and being suitable for performing an expansion in an objectto be dilated, the balloon structure comprising a wall which has,transverse the longitudinal extent, at any point, an annularcross-section delimited externally by an outer surface which, at leastin an intermediate portion, is suitable for coming into contact with theobject to be dilated, and internally by an inner surface which delimitsan inflation chamber, in which at least one wall cavity is provided inthe wall and is formed within the annular cross-section which delimitsthe inflation chamber, so as to be disposed between the outer surfaceand the inner surface, the cavity extending without interruptions and/oropenings, longitudinally relative to the balloon structure, between theproximal end and the distal end.
 102. A method of producing a balloonstructure said balloon structure being of predominant longitudinalextent with a proximal end and a distal end, and being suitable forperforming an expansion in an object to be dilated, the balloonstructure comprising a wall which has, transverse the longitudinalextent, at any point, an annular cross-section delimited externally byan outer surface which, at least in an intermediate portion thereof, issuitable for coming into contact with the object to be dilated, andinternally by an inner surface which delimits an inflation chamber, inwhich: at least one wall cavity is provided in the wall and is formedwithin the annular cross-section which delimits the inflation chamber soas to be disposed between the outer surface and the inner surface thecavity extending, without interruptions and/or openings, longitudinallyrelative to the balloon structure between the proximal end and thedistal end so that, when the balloon structure is inflated or expanded,the outer surface of the intermediate portion has, in cross-sectiontransverse the longitudinal extent of the balloon structure, uniformcurvature around the entire annular extent of the cross-section; saidmethod provides for the steps of: providing a tubular duct ofpredominant longitudinal extent, provided with at least two cavitieswhich extend along its entire longitudinal extent whilst remainingseparate from one another, between proximal openings and distalopenings, inserting at least a portion of the duct in a die providedwith a cavity that is widened to form the desired shape of the expandedballoon, closing in a leaktight manner one of the distal and proximalopenings, or sections of the duct outside the die, of at least onecavity to be expanded, heating the portion of duct that is disposed inthe die to a temperature which permits permanent deformation of thematerial or of one of the materials which constitute the tubular duct,at least in the region of the cavity to be expanded, admitting fluidunder pressure to the cavity to be expanded so as to deform the wall ofthe duct which delimits the cavity, causing the wall to fit against thewalls of the widened cavity delimited by the die, the second cavityremaining incorporated in the wall thus deformed.
 103. A methodaccording to claim 102, in which, before the admission of fluid underpressure to one of the cavities, a stylet is inserted in the othercavity so as to prevent the deformation of the heated wall fromobstructing this other cavity.
 104. A method according to claim 103, inwhich the stylet is coated with non-stick material such as, for example,Teflon™.
 105. A balloon catheter comprising a balloon structure, saidballoon structure being of predominant longitudinal extent with aproximal end and a distal end, and being suitable for performing anexpansion in an object to be dilated, the balloon structure comprising awall which has, transverse the longitudinal extent, at any point, anannular cross-section delimited externally by an outer surface which, atleast in an intermediate portion thereof, is suitable for coming intocontact with the object to be dilated, and internally by an innersurface which delimits an inflation chamber, in which: at least one wallcavity is provided in the wall and is formed within the annularcross-section which delimits the inflation chamber so as to be disposedbetween the outer surface and the inner surface the cavity extending,without interruptions and/or openings, longitudinally relative to theballoon structure between the proximal end and the distal end so that,when the balloon structure is inflated or expanded, the outer surface ofthe intermediate portion has, in cross-section transverse thelongitudinal extent of the balloon structure, uniform curvature aroundthe entire annular extent of the cross-section.
 106. A catheteraccording to claim 105, which includes an apex tip which has a proximalend and an apex end and comprises: a tubular apex portion disposed inthe vicinity of the apex end, and a proximal connecting tube disposed inthe vicinity of the proximal end, in which: the proximal connecting tubeis partially housed with a distal portion thereof inside a proximalportion of the apex tube, the connecting tube being connected to theapex tube so as to form a cavity which extends without interruption froman opening disposed at the proximal end of the connecting tube to anopening disposed at the apex end of the apex tube, the connecting tubebeing suitable for connection to a wall cavity suitable for housing aguide wire, the wall cavity being provided within a wall which delimitsa balloon inflation chamber.
 107. A catheter according to claim 105,comprising an apex tip which has a proximal end and an apex end andcomprises: a tubular apex portion disposed in the vicinity of the apexend, a proximal connecting tube disposed in the vicinity of the proximalend, and a tube for anchoring a thrust wire or rod, also disposed in thevicinity of the proximal end, in which: the anchoring tube and theproximal connecting tube are arranged at least partially side by sideand are housed with respective distal portions inside a proximal portionof the apex tube, the connecting tube being connected to the apex tubeso as to form a cavity which extends without interruption from anopening disposed at the proximal end of the connecting tube to anopening disposed at the apex end of the apex tube, the connecting tubebeing suitable for connection to a wall cavity suitable for housing aguide wire, the wall cavity being provided within a wall which delimitsa balloon inflation chamber, the anchoring tube being suitable forconnection to a distal opening of a balloon structure for the leaktightclosure thereof and for the anchorage of a distal end of a thrust wireprovided inside the balloon.
 108. A catheter according to claim 107 inwhich the anchoring tube, the connecting tube, and the apex tube arewelded to form a single body.
 109. A catheter according to claim 105including an apex tip which has a proximal end and an apex end andcomprises: a tubular apex portion disposed in the vicinity of the apexend, a first proximal connecting tube disposed in the vicinity of theproximal end, and a second connecting tube, also disposed in thevicinity of the proximal end, in which: the first connecting tube andthe second connecting tube are arranged at least partially side by sideand are housed with respective distal portions inside a proximal portionof the apex tube, the first and second connecting tubes being connectedto the apex tube so as to form cavities which extend withoutinterruption from respective openings disposed at the proximal ends ofthe connecting tubes to at least one opening disposed at the apex end ofthe apex tube, the first connecting tube being suitable for connectionto a wall cavity suitable for housing a guide wire, the wall cavitybeing provided within a wall which delimits a balloon inflation chamber,the second connecting tube being suitable for connection to a guide-wireduct suitable for housing a guide wire, the guide-wire duct beingdisposed within the balloon structure.
 110. A catheter according toclaim 109, in which the first and second connecting tubes and the apextube are welded to form a single body.
 111. A catheter according toclaim 95, in which the thrust wire is disposed inside the catheter shaftconnected proximally to the balloon.
 112. A catheter according to claim105, in which the guide-wire duct is disposed inside the catheter shaftwhich is connected proximally to the balloon.
 113. A catheter accordingto claim 105, in which the wall portion which separates the wall cavityfrom the outer surface has an opening which forms a lateral aperture forallowing a guide wire to be inserted in the wall cavity or to emergetherefrom.
 114. A catheter according to claim 105, in which the balloonstructure is connected proximally to a shaft comprising an inflationcavity connected to the inflation chamber in a leaktight manner for theflow of a fluid from the shaft to the inflation chamber and vice versa.115. A catheter according to claim 105, in which the balloon structureis connected proximally to a shaft comprising a guide-wire cavityconnected to the wall cavity in a leaktight manner for the passage of aguide wire.
 116. A catheter according to claim 115, in which theguide-wire cavity is disposed in the wall of the shaft and is separatedfrom the outer surface of the shaft by a wall portion.
 117. A catheteraccording to claim 116, in which the shaft has an opening in the wallportion which separates the guide-wire cavity from the outer surface,the opening being suitable for the passage of a guide wire.
 118. Acatheter according to claim 105, in which the balloon structure isconnected proximally to a shaft comprising a guide-wire cavity connectedto the wall cavity in a leaktight manner for the passage of a guidewire, the guide-wire cavity being provided in a guide-wire duct providedinside the shaft.
 119. A catheter according to claim 118, in which theduct is connected in a leaktight manner to a lateral opening provided inthe outer wall of the shaft to allow a guide wire to be inserted in theguide-wire cavity of the guide-wire duct or to emerge therefrom.
 120. Acatheter according to claim 105, in which the shaft has a plurality ofportions formed with a plurality of ducts.
 121. A catheter according toclaim 105, in which the shaft has a plurality of portions formed withducts made of different materials and/or with different thicknesses.122. A catheter according to claim 105, in which the shaft has aninflation cavity that is in flow communication with the inflationchamber of the balloon structure, and a thrust wire having a distal endand a proximal end.
 123. A catheter according to claim 122, in which thethrust wire is inside the inflation cavity.
 124. A catheter according toclaim 122, in which the thrust wire extends along the entire length ofthe shaft.
 125. A catheter according to claim 122, in which the thrustwire is anchored by its distal end to the balloon structure.
 126. Acatheter according to claim 122, in which the thrust wire is anchored byits distal end to the tip of the catheter.
 127. A catheter according toclaim 122, in which the thrust wire is connected by its proximal end toan inner tube that is present in the shaft.
 128. A tip for a cathetersuch as a catheter for angioplasty or for depositing an endolumenalprosthesis or stent in a duct, for example, a vascular duct, the tiphaving a proximal end and an apex end and comprising: a tubular apexportion disposed in the vicinity of the apex end, and a proximalconnecting tube disposed in the vicinity of the proximal end, in which:the proximal connecting tube is partially housed with a distal portionthereof inside a proximal portion of the apex tube, the connecting tubebeing connected to the apex tube so as to form a cavity which extendswithout interruption from an opening disposed at the proximal end of theconnecting tube to an opening disposed at the apex end of the apex tube,the connecting tube being suitable for connection to a wall cavitysuitable for housing a guide wire, the cavity being provided within awall which delimits a balloon inflation chamber, the apex tube beingconnected proximally in a leaktight manner to a distal opening of aballoon structure for the leaktight closure thereof.
 129. A tip for acatheter such as a catheter for angioplasty or for depositing anendolumenal prosthesis or stent in a duct, for example, a vascular duct,the tip having a proximal end and an apex end and comprising: an apextubular portion disposed in the vicinity of the apex end, a proximalconnecting tube disposed in the vicinity of the proximal end, and a tubefor anchoring a thrust wire or rod, also disposed in the vicinity of theproximal end, in which: the anchoring tube and the proximal connectingtube are arranged at least partially side by side and are housed withrespective distal portions inside a proximal portion of the apex tube,the connecting tube being connected to the apex tube so as to form acavity which extends without interruption from an opening disposed atthe proximal end of the connecting tube to an opening disposed at theapex end of the apex tube, the connecting tube being suitable forconnection to a wall cavity suitable for housing a guide wire, thecavity being provided within a wall which delimits a balloon inflationchamber, the anchoring tube being closed distally in a leaktight mannerand suitable for connection to a distal opening of a balloon structurefor the leaktight closure thereof and for the anchorage of a distal endof a thrust wire.
 130. A tip according to claim 129 in which theanchoring tube, the connecting tube, and the apex tube are welded toform a single body.
 131. A tip for a catheter such as a catheter forangioplasty or for depositing an endolumenal prosthesis or stent in aduct, for example, a vascular duct, the tip having a proximal end and anapex end and comprising: a tubular apex portion disposed in the vicinityof the apex end, a first proximal connecting tube disposed in thevicinity of the proximal end, and a second connecting tube, alsodisposed in the vicinity of the proximal end, in which: the firstconnecting tube and the second connecting tube are arranged at leastpartially side by side and are housed with respective distal portionsinside a proximal portion of the apex tube, the first and secondconnecting tubes being connected to the apex tube so as to form cavitieswhich extend without interruption from respective openings disposed atthe proximal ends of the connecting tubes to at least one openingdisposed at the apex end of the apex tube, the first connecting tubebeing suitable for connection to a wall cavity suitable for housing aguide wire, the cavity being provided within a wall which delimits aballoon inflation chamber, the second connecting tube being suitable forconnection to a guide-wire duct suitable for housing a guide wire, theguide-wire duct being disposed inside the balloon structure.
 132. A tipaccording to claim 131, in which the first and second connecting tubesand the apex tube are welded to form a single body.
 133. A method forthe production of a tip, said tip having a proximal end and an apex endand comprising: a tubular apex portion disposed in the vicinity of theapex end, and a proximal connecting tube disposed in the vicinity of theproximal end, in which: the proximal connecting tube is partially housedwith a distal portion thereof inside a proximal portion of the apextube, the connecting tube being connected to the apex tube so as to forma cavity which extends without interruption from an opening disposed atthe proximal end of the connecting tube to an opening disposed at theapex end of the apex tube, the connecting tube being suitable forconnection to a wall cavity suitable for housing a guide wire, thecavity being provided within a wall which delimits a balloon inflationchamber, the apex tube being connected proximally in a leaktight mannerto a distal opening of a balloon structure for the leaktight closurethereof; said method provides for the steps of: providing an apex tubehaving a proximal end and a distal end in which an apex opening isprovided, widening a proximal portion of the apex tube, providing aconnecting tube suitable for insertion in a wall cavity of a balloonstructure, the wall cavity being suitable for housing a guide wire,inserting a distal portion of the connecting tube in the widened portionof the apex tube so as to form a continuous cavity between a proximalopening of the connecting tube and the apex opening of the apex tube.134. A method according to claim 133, which provides for the furtherstep of: providing an anchoring tube to be inserted with a distalportion thereof in the apex tube so as to be disposed at least partiallybeside the connecting tube, the anchoring tube being suitable foranchoring a thrust wire and being suitable for the leaktight closure ofa distal opening of an inflation chamber of a balloon structure.
 135. Amethod according to claim 133, which provides for the further step of:providing a second connecting tube to be inserted with a distal portionthereof in the apex tube so as to be disposed at least partially besidethe first connecting tube, the connecting tube being suitable forforming a second guide-wire cavity between a proximal opening of thesecond connecting tube and the apex opening of the apex tube, and beingsuitable for the leaktight closure of a distal opening of an inflationchamber of a balloon structure.
 136. A balloon catheter, such as acatheter for angioplasty or for depositing an endolumenal prosthesis orstent in a duct, for example, a vascular duct, comprising: a shaft inwhich an inflation cavity is provided, the inflation cavity having aproximal end and a distal end, an inflatable balloon having a proximalend and a distal end, delimiting an inflation chamber, in which thedistal end of the inflation cavity opens in flow communication with theinflation chamber, a tip which closes the distal end of the balloon in aleaktight manner and has a connecting duct provided with a cavity whichhas a proximal end and an apex end, the balloon comprising a wall whichhas, transverse the longitudinal extent, at any point, an annularcross-section delimited externally by an outer surface which, at leastin the intermediate portion, is suitable for coming into contact with anobject to be dilated, and internally by an inner surface which delimitsan inflation chamber, in which: at least one cavity is provided in thewall, and is formed, for its entire extent in the wall of the balloon,within the annular cross-section which delimits the inflation chamber soas to be disposed between the outer surface and the inner surface, andthe cavity extends without interruptions and/or openings, longitudinallyrelative to the balloon structure, between the proximal end and thedistal end of the balloon.
 137. A catheter according to claim 136, inwhich a thrust wire is provided in the inflation cavity.
 138. A catheteraccording to claim 137, in which the thrust wire extends with its distalend as far as the tip of the catheter.
 139. A catheter according toclaim 138, in which the distal end of the thrust wire is anchored to thetip.
 140. A catheter according to claim 136, in which, when the balloonstructure is inflated or expanded, the outer surface of the intermediateportion has, in cross-section transverse the longitudinal extent of theballoon structure, uniform curvature around the entire annular extent ofthe cross-section.
 141. A method for the use of a catheter comprising aballoon structure said balloon structure being of predominantlongitudinal extent with a proximal end and a distal end, and beingsuitable for performing an expansion in an object to be dilated, theballoon structure comprising a wall which has, transverse thelongitudinal extent, at any point, an annular cross-section delimitedexternally by an outer surface which, at least in an intermediateportion thereof, is suitable for coming into contact with the object tobe dilated, and internally by an inner surface which delimits aninflation chamber, in which: at least one wall cavity is provided in thewall and is formed within the annular cross-section which delimits theinflation chamber so as to be disposed between the outer surface and theinner surface the cavity extending, without interruptions and/oropenings, longitudinally relative to the balloon structure between theproximal end and the distal end so that, when the balloon structure isinflated or expanded, the outer surface of the intermediate portion has,in cross-section transverse the longitudinal extent of the balloonstructure, uniform curvature around the entire annular extent of thecross-section; said method provides for the steps of: inserting a guidewire in a vessel which is to be operated on, fitting a catheter,provided with the balloon structure, on the guide wire, passing the wirethrough an apex guide-wire aperture, sliding it through a guide-wirewall cavity which, at least for its section corresponding to the extentof the balloon, is disposed in the balloon wall, and causing the wire toemerge from a proximal aperture, relative to the balloon, inserting thecatheter in the vessel, passing it along the guide wire until theballoon is disposed in the operation zone.
 142. A method according toclaim 141, which provides for the further step of: advancing thecatheter on the guide wire by pushing it by means of a thrust wireprovided in the catheter body.